Elevator control



June 20, 1961 R. MOSER 2,989,148

ELEVATOR CONTROL Filed Nov. 5, 1959 3 Sheets-Sheet 1 1F 51 2 Ax Hg June20, 1961 R. MosER ELEVATOR CONTROL Filed Nov. 5, 1959 Fig. 6

RV 2 K381 K2RU2 RU 2 3 Sheets-Sheet 5 K2 RS 2 K2 RS3 K4 RV1 i if&

This invention relates to elevator controls, and more particularly, toan elevator control circuit for an elevator control system to preventundesired operation of an elevator cab.

It is important to provide in an elevator control system, controls andindicating devices which are efiective to provide at all times apositive control and indication of operation of an elevator cab. Use ismade of mechanically free, but magnetically related elements in order todetermine whether a shaftway door on one of the floors or stops for theelevator cab is open, whether the shaftway door is locked and whetherthe elevator cab cable is in a released position so that the elevatorcab may be raised or lowered thereby.

This application is a combination-impart of my US. patent applicationSerial No. 723,560 filed March 24, 1958 for Elevator Control, nowabandoned. Reference is made to copending U.S. patent application SerialNo. 703,173 filed December 16, 1957 for Safety Device for Elevator Doorand U.S. patent application Serial No. 848,719 filed October 26, 1959which is a continuationin-part of application 703,173 in the name ofRichard Moser et al. which application describe saturable magneticdevices and other mechanically free but magnetically related deviceswhich may be used to energize the elevator control circuit of thepresent invention.

It is an object of the present invention to provide a positive, quickacting safety circuit which is responsive to electrical impulses forindicating the position of mechanical elements.

In order to accomplish the foregoing object, the present inventionproposes the provision of related switching devices, such as transistorelements in which the collector-emitter circuit is maintained in anon-conductive condition and rendered conductive when an impulse isapplied to the base of the transistor whereby to render thecollector-emitter circuit conductive for energizing a relay so thatswitch contacts for the safety circuits are energized.

It is further proposed to provide a group of interrelated transistorcircuits in which the base of one transistor circuit is renderedselective when the collector-emitter cincuit of another transistor isrendered conductive. Proper sequence of operation is obtained inaccordance with the energization of the transmitting elements whichcomprise saturable magnetic devices having a high degree of rapidresponse to a change in position of the shaftway door, lock for theshaftway door and emergency circuit for the elevator cab. While theinvention is described herein in the context of elevator controlcircuits for elevator control systems, it will be appreciated that italso has application to other problems of circuit controls.

For a better understanding of the invention, as Well as other objectsand further features thereof, reference is had to the following detaileddescription to be read in "conjunction with the accompanying drawings,wherein like components in the several views are identified by likereference numerals.

In the drawings:

FIG. 1 is an elevational view partially in section illustrating ashaftway door with a door locking mechanism and a closing controldevice;

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FIG. 2 is an enlarged sectional view of a transmitting elementcomprising a pair of saturable magnetic devices for controlling theclosing control device for the shaftway door;

FIG. 3 is a transverse section of the shaftway door showing the doorlocking control mechanism together with transmitting device comprising asaturable magnetic device therefor;

FIG. 4 shows a transmitting device comprising a saturable magneticdevice for safety contacts to control the movement of the elevator cabcable; and

FIGS. 5 and 6 show two parts of a schematic wiring diagram for anelevator control system.

Referring now to FIG. 1 which shows an elevator shaftway door 50 and itsassociated door frame or iamb 51. Positioned at the top of door 50 andhoused in the door frame 51 is a transmitting element 11 for controllingthe closing position of the door. Mounted in the door frame 51 is alocking mechanism 60 comprising a roller lever 61 and a locking bolt 63actuated thereby. An outside call button DA for calling an elevator cab,not shown, is also provided on the door frame 51. While only a singleshaftway door 50 together with its associated elements has been shown,it will be understood that each floor of a structure provided with anelevator shaftway and cab may be provided with the same or similar door50 together with its components.

Referring now to FIG. 2, the transmitting element 11 comprises two coilsor windings 52 and 53 interconnected on one side by means of an ironplate 56 and on the other side fixed to the door frame 51. Affixed tothe side of the door Sil facing the shaftway is a core 54 pro 'videdwith two core legs 54' and 54" which fit within coils 52 and 53,respectively, the door frame being provided with an opening 55 slightlylarger than core 54 so that it can fit within opening 55 and with itslegs 54' and 54" in coils 52 and 53 when the door is in its closedposition. Coil 52 is excited by an alternating current as will beexplained subsequently in connection with the circuit of FIGS. 5 and 6which produces a flux in the core 54 when the door 50 is closed and theiron plate 56, and, by transformer action coil 52 induces an alternatingcurrent voltage in coil 53. When the door 50 is in its open position,the iron plate 56 immediately becomes saturated when some A.C. currentflows through coil 52 so that there is presented a high impedance to theflow of A.C. current through the coil 52. When iron plate 56 causes coil52 to present a high impedance to the flow of current therethrough,practically none or a negligible A.C. voltage is induced into coil 53 byiron plate 56 and coil 52 since a very small or no A.C. current flowsthrough coil 52 so that there is no flux linkages between coils 52 and53. When the door 50 is closed core legs 54 and 54 are positioned withincoils 52 and 53 and coil 52 presents a low impedance to the flow of A.C.current therethrough, since core 54 is made of a saturable magneticmaterial.

Referring now to FIG. 3 of the drawings which shows the lockingmechanism 60 to maintain door 50 in a locked condition to an enlargedscale and comprises a housing 62 of magnetically non-conductive materialtogether with the locking bolt 63 guided therein. The locking boltcooperates with a locking lever 64 which is actuated by the roller lever(see FIG. 1). When the door is closed, the locking bolt 63 engages theshaftway door 50 and prevents an unintentional opening of same. Housing62 is provided with a pair of aligned apertures which are aligned withan aperture in the door frame 51 and shaftway door 5'0 in the closedposition thereof. The pair of apertures in the housing 62 guide themovement, shown as being in a horizontal direction, of the locking 3bolt 63, and the apertures in the door and door frame are aligned toprovide the locking action.

Housing 62 also contains a transmitting device comprising a core 65 ofsaturable magnetic mateiial having a Winding 67 thereon and juxtaposedto core 65 is a core 66 made of saturable magnetic material and having awinding 68 thereon. Cores 65 and 66 are positioned relative to eachother so as to provide an air gap therebetween into which moves amagnetically short circuiting lug or plate 69 having a leg which isfixedly coupled to locking bolt 63 for movement therewith. When lockingbolt 63 is moved so as to become engaged with the aligned apertures inthe door frame and door, the lug 69 is moved outside of the air gapbetween cores 65 and 66. The coil 67 is energized with alternatingcurrent producing in the core 65 a change of flux which is transmitted,when the door is locked, by way of the air gap to the core 66 andinduces therein an alternating current potential in the winding 68. Ifthe door is unlocked, the short-circuit lug 69 enters the air gap andinterrupts the flux between the cores 65 and 66 so that no flux isinduced in winding 68 causing it to be free from voltage. Consequently,no A.C. current is induced in winding 68 by winding 67.

FIG. 4 shows a contactless or mechanically free, but magneticallyrelated transmitting element 1 of the type used for safety contacts insafety circuits, for example, slack rope switch contacts, safety brakecontacts, etc. Transmitting element 1 comprises a housing 75 which isconvered by a cover 76 having an opening through which passes a corebolt 80. Fixed on the bottom of the housing is a double coil structure77 comprising two windings or coils 78 and 79. The core bolt 80 which isguided in the housing 75 and cover 76 is composed of two members, a core81 extending into the hollow space of the double coil structure 77 and aguide pin 82 provided with a shoulder made of a non-magnetizablematerial which is pressed into the core 81 by means of a pin 87. Thecore 81 is maintained in the position shown in the drawing by means of aspring 83 bearing on coil structure 77 and the shoulder of the guide pin82. The winding 78 is energized with an alternating current and a fluxinduced into the core 81 induces an alternating potential in the winding79. If a force acts on the core bolt 80 forcing it against the forceexerted by the spring 83, the core 81 moves out of reach of the winding78 so that it is no longer possible to induce an alternating currentinto the core 79. Core bolt 80 may be used as an emergency button toprovide for an automatic gripping of the elevator cables 95 and preventoperation or movement of cab 94. It will be understood that when theshoulder of guide pin 82 becomes engaged with the double coil structure77, the shank portion 82 of the guide pin 82. is moved into the positionformerly held by core 81 and since it is of non-magnetic material, theflux linkages between windings 78 and 79 are negligible so that they maybe ignored. An elevator cab 94 (diagrammatically shown in FIG. 5) issupported by the usual elevator cables 95 (only one being shown). Attheir ends these cables 95 are provided with a conical head 99 coactingwith a conical seat in a top plate of an upper frame 100 connected tothe cab 94-. A safety lever 103 is pivotally mounted betweentransmitting element 1 arranged on the top of the cab 94 and the topplate of the frame 100 and held in horizontal position by means of aspring 104. Upon a break of cable 95 the conical head 99 falls out ofits seat onto the safety lever 103 which in turn rocks downwardly andpushes the core bolt 89 into the housing 75 thereby to displace core 81from its position as shown in FIG. 4 and move the guide pin 82 into thisposition so as to prevent the energization of winding 79 by winding 78.

Referring now to FIG. 5 of the drawings which illustrates a novelcircuit for an elevator control system, a three phase power sourcehaving conductors R, S and T is provided for energizing an elevatormotor 90. Motor is of the reversible type, and switches RUl' and RUZ arecoupled to conductors S and T and motor 90 for providing upward motionand downward motion, respectively, to the elevator cab 94. As is wellknown, in elevator devices, the driving motor 90 drives a gear drive 92by way of a brake 91 composed of brake disc, brake shoe and brakingmagnet solenoid MB. A driving pulley 93 is fixed on the slowly runningshaft of the gear drive 92, the elevator cab 94 being suspended from oneend and a counterweight 96 being suspended from the other end of thecable which is guided over the pulley 93. Call buttons DC are arrangedin the cab 94-. Fixed on the cab is a movable slideway 97 which actuatesshaft switches JS1-3 fixed in the shaftway, one of which switches I8 isassociated with each stop or floor. A locking magnet MV which cooperateswith a movable slideway 98 is also mounted on the cab; the slideway 98actuates the roller lever 61 (FIG. 1) and the door lock 60 (FIG. 3)connected to the latter. The novel circuit will be explained inconnection with an elevator control system which is adapted for threefloors or stops, it being understood that any number of n stops orfloor-s may be provided.

Also coupled to conductors S and T is a primary winding of an iron coretransformer Tr1 having two secondary windings and 111. The generalsymbols used in the wiring diagram are set forth as follows:

DA13Outside or door call buttons DC13Cabin call buttons JS13fiShaftswitches KJSl-3Switch contacts of the shaft switches KRSAwitch contactsof the floor relays KRUAwitch contacts of the relays KRVSwitch contactsof the pilot or pre-control relays RSl-3Floor relays RUlRelay for upwardmotion RUZ-Relay for downward motion RV--Pilot or pre-control relay Onesecondary winding 110 of the transformer Trl is coupled to a rectifierGL1, the positive output of which is connected to a common positiveconductor 1000 and the negative output of which is connected to a commonnegative conductor 101 of the elevator control.

The secondary winding 111 of the transformer Tr1 is connected to theconductors 112 and 113 connected to a three-part safety circuit whichforms the subject matter of this invention.

The first part of the safety circuit comprises the transmitting element1 for the safety contacts and includes a winding 78 coupled toconductors 112 and 113. FIG. 4 illustrates the typical contactless ormechanically free, but magnetically related-transmitting element 1 ofwhich winding 78 forms a part together with its associated winding 79.Another transmitting element 2 comprising windings 78 and 79 identicalwith the element 1 of FIG. 4 is also shown schematically with thewindings 79 of elements 1 and 2 connected together in series. Thetransmitting elements 1 and 2 are mounted on the cab 94 for the controlof the gripping or safety and slack cable device.

One free end of the winding 79 of the transmitting element 1 isconnected to the base of an amplifying element such as a transistor 6.The collector of the transistor 6 leads by way of a circuit element, forexample, a relay RT1, to the conductor 101. A smoothing condenser 10 isconnected in parallel with and by-passes the relay RT1 to smooth thecurrent energizing relay RT1 and to prevent arcing and a false holdingat the contacts thereof. The emitter of the transistor 6 is connected toa neutral or grounded conductor 102 by means of a conductor 114. Alimiting (peak-limiter) diode 7 is arranged between the emitter and thebase of the transistor. A compensation or voltage balancing network 5composed of resistors 115- and 116 connected in series is arrangedbetween the conductors 114 and 1000. The other free end of the winding79 of the transmitting element 2 is connected to the voltage balancingnetwork 5 to the common connection of resistors 115 and 116, the otherends of which are coupled to conductors 102 and 1000, respectively.

The second part of the safety circuit comprises contactless ormechanically free, but magnetically related transmitting elements 11, 12and 13 for the safety control device of the shaft way doors 50; whileonly transmitting element 11 is shown in FIG. 2, it is understood thatelements 12 and 13 are identical with element 11. The conductors 112 and113 are also connected to the second part of the safety circuit with thewindings 52 of the contactless transmitting elements 11, 12, 13 for theclosing controls of the doors according to FIG. 2. One end of thewinding 53 of the transmitting element 11 is connected to the base of anamplifying element such as a transistor 17, while the other end isconnected by means of a conductor 124 to a voltage balancing network 14comprising the resistors 120, 121, 122 and 123 connected in series, theresistor 120 being connected to the conductor 101 and the resistor 123being connected to the conductor 1000. Similarly, one end of thewindings 53 of the transmitting elements 12 and 13 are connected by wayof conductors 125 and 126 to the voltage balancing networks 15 and 16,respectively, the voltage balancing networks consisting of the resistors120-123. The other ends of windings 52 of elements 12 and 13 are coupleddirectly to the base of transistors 18 and 19, respectively. Theemitter-collector circuit of transistors 17, 18 and 19' leads from theconductor 102 to the emitter of transistor 19 and by way of thesequentially connected collectors and emitters of the transistors 19, 18and 18, 17, the collector of transistor 17 and circuit element, forexample, relay RT2 to the conductor 101. A smoothing condenser 23 of thesame type as condenser 10 is connected in parallel to the relay RT2.

The third part of the safety circuit comprises the locking mechanism 60,previously described in connection with FIG. 3 of the drawings,comprising a winding 67 for each of identical contactless ormechanically free, but magnetically related transmitting elements 25 26and 27. While only transmitting element 25 is shown in FIG. 3, elements26 and 27 are identical with element 25, it being understood that anelement such as element 25 is provided for each shaftway door. Eachwinding 67 is coupled to conductors 112 and 113 and is magneticallyrelated to an associated or secondary winding 68. One end of the winding68 of transmitting element 25 leads to the base of an amplifying elementsuch as a transistor 29 while the other end is connected to a voltagebalancing network 32 consisting of resistors 130 and 131, the resistor130 being connected to the emitter of a transistor at a connection point137 and the resistor 13 1 being connected to the conductor 1000. Thereare n balancing networks, one for each of the 11' stops and ntransistors associated therewith. All of the balancing networks with theexception of the nth balancing network are coupled similarly. Theemitter of transistor 30 is also coupled from the connection point 137through a resistor 36 which is by-passed by a smoothing condenser 40 toconductor 102.

In a similar manner, winding 60 of transmitting element 2.6 has one endcoupled to the base of a transistor 30 and the other end to a voltagebalancing network 33 comprising resistors 132 and 133. The resistor 132of the voltage balancing network 33 leads to the emitter of thetransistor 31, at a connection point 136 and the resistor 133 is coupledto conductor 1000. The emitter of transistor 31 is coupled from theconnection point 136 through a resistor 37 which is bypassed by asmoothing condenser 41 conductor 102. Winding 68 of element 27 has oneend coupled to the base of a transistor 31 and the other end coupled toa voltage balancing network 34 comprising resistors 134 and 135.Resistor 134 which is part of nth balancing network is coupledto'conductor 101 and resistor 135 is also coupled to conductor 1000.Also coupled to conductor 101 are the collectors of the transistors 29,30 and 3 1. The emitter of the transistor 29 is connected by way of acircuit element, for example, a relay RT3, to the conductor 102. Asmoothing condenser 39 is connected in parallel to the relay RT3.

Also coupled between the negative and positive conductors 101 and 1000are a number of additional circuit elements for the elevator controlsystem; with the elevator cab 94 stopped at the second floor, thecircuit elements are shown in their normal position. In the line ofconductor 101, switch contacts KRTI and KRTZ are shown in their normallyclosed position indicating that their associated relays RT1 and RT2,respectively, are energized. Coupled between conductors 101 and 1000 arethe circuits for energizing relays RS1, RS2, RS3, RV1, RV2, RU1 and RU2,magnet MV and braking solenoid MB when the switches in the circuits areclosed. The relay RS1 is coupled from conductor 1000 through theparallel circuit of the outside call button DAl and cabin call buttonDC1 through braking solenoid switch KMB to conductor 101; switches -DA-1and D01 are shown in their open position to maintain the relay RS1deenergized. Similarly, the relays RS2 and RS3 are coupled through theirassociated call buttons DA2, IDA-3 and DC2, DC3, respectively, tobraking solenoid switch KMB. Switch contacts K1RS1, K1RS2 and K1RS3 arecoupled through holding switch K1RV1K1RV2 between conductors 101 and1000. When relays RS1, RS2 or RS3 are energized, switch contacts K1RS1,K1RS2 or K1RS3 and KZRSI, K2RS2 or K2RS3, respectively, are closed. Thecontact shaft switches K181 are normally closed when the cab is not atthe stop or floor; since cab 94 is at the second stop switch contactsK181 and K183 are shown in their closed position with switch contactKJSZ shown in its open position. The relay RV1 is coupled from conductor1000 and is coupled through contact switches K2RV2, KISS and K2RS3 orKJS2, K2RS2 to conductor 101; similarly, relay RV2 is coupled fromconductor 1000 through contact switches K2RV1, K181 and K2RS1 or KJSZ,KRSZ to conductor 101. When relay RV1 is energized, switch contactsKIRVl, K3RV1 and K4-RV1 are closed, and when relay RV2 is energized,switch contacts KlRVZ, K3RV2 and K4RV2 are closed. Energization ofcontact switch K1RV1 or K1RV2 completes the holding circuit for relaysRS1, RS2 or RS3 causing them to remain energized after the outside callbuttons or cab call buttons are released.

Relay RT is deenergized when any one of the shaftway doors 50 is openand is energized when all shaftway doors 50 are locked. Switch contactKRT3 is closed when relay RT3 is energized. Relay -RU1 is coupledbetween conductors 1000 and 101 through switch contacts KZRUZ, K4RV2 andKRT3, and relay RU2 is coupled between conductors 1000 and 101 throughswitch contacts K2RV1 and KRT3. Relay RU1 is energized when relays RV2and RT3 are energized to close switch contacts K4RV2 and I IRT3 andcause switch contact RUl to close. Similarly, switch contacts RUZ areclosed when relay RUZ is energized after relays RV1 and RT?) areenergized to closed switch contacts K4RV1 and KRT3. Switch DH is amaster control switch which when opened prevents operation of theelevator cab 94 by maintaining brake 91 locked since the circuit betweenconductors 101 and 1000 is open.

The braking solenoid MB is coupled between conductors 1000 and 101through the parallel connection of switches KlRUl and K1RU2. When switchcontrol K1RU1 or K2RU2 is closed, the braking solenoid MB is effectiveto release the brake shoe of brake 91 from the disc thereof to permitthe cab 94 to move. Locking magnet MV is coupled between conductors 1000and 101 through the parallel connection of switch contacts K3RV1 andK3RV2. When switch contacts K3RV1 or K3RV2 is closed, locking magnet MVis energized in order to main tain the door 50 for each stop or floor inits locked condition, and when locking magnet MV is deenergized, thedoor 50 at the stop may be opened. Switch contacts K2RV1, K2RV2, whenopened serve to maintain the relays RUI and RUZ deenergized whenservicing or performing a maintenance operation.

As shown in FIG. 6, the cab 94 is in a position of rest at the secondstop, since the contact KJSZ of the shaft switch 182 is in middleposition. The windings 78 of the transmitting elements 1, 2 (FIG. 5) forcontrolling the gripping or safety device and the slack cables areexcited. The voltages induced in the windings 79 reach the base-emittercircuit of the transistor 6 by way of the voltage balancing network 5and conductor 114.

The potential of the voltage balancing network 5 is so selected that, inthe absence of any induced voltage in any of the transmitting elements 1or 2, the voltage at the base of the transistor 6 becomes positive withrespect to the emitter and blocks the collector-emitter circuit. Wherethere are provided a larger number of sequentially connected windings79, with corresponding selection of the voltage balancing network 5, thelimiting diode 7 prevents a rise of a positive voltage which would bedetrimental to the transistor 6. Only when all induced voltages arepresent in the windings '79, will a part of the negative half-Wave ofthe sequentially connected transmitting elements 1 or 2 overcome thepositive potential of the voltage balancing network 5 causing the baseof the transistor 6 to become negative with respect to the emitter andthe collector-emitter circuit to become conductive, so that a pulsatingdirect current flows from the conductor 102 through conductor 114,transistor 6 and relay RT1 to the conductor 101 and operates relay RT1.The condenser 10 serves to smoothen the pulsating direct current flowingthrough the relay RT1 in order to prevent the relay from buzzing orvibrating.

The windings of the transmitting elements 11, 12, 13 for the safetycontrol device of the doors are excited. The voltages induced in thewindings 53 act by way of the voltage balancing networks 14 or 15 or 16of the baseemitter circuit of the corresponding transistors 19, 18, 17.The values of the potentials of the voltage balancing networks 14, 15,16 are so selected that, in case of possibly occurring rest potentialsin the windings 52 with the doors open, the potentials at the bases ofthe transistors 17, 13, 19 can never become negative with respect to theemitters.

Only when the door is closed and and the induced potential is present inthe winding 53 of the transmitting element 11 or 12 or 13, will thenegative-wave overcome the positive potential of the voltage balancingnetwork 14 or 15 or 16, thereby causing the bases of the transistors 17or 18 or 19 to become negative with respect to their emitters and causethe collector-emitter circuits to become conductive. When allcollector-emitter circuits of the transistors 17, 18, 19 are conductive,a pulsating direct current is caused to flow from the conductor 102 byway of the transistors 19, 18, 17 and through the relay RT2 to theconductor 101 causing an attraction or energization of the relay RT2.

When the windings 67 of the transmitting elements 25, 26, 27 (FIG. 6)for controlling the locking of the doors are also energized, then thepotentials induced in the windings 68 act through their associatedvoltage balancing networks 32, 33, 34 on the base-emitter circuits ofthe transistors 29, 30 and 31. The value of the potentials of thevoltage balancing networks 32, 33, 34 is so selected that, in case ofpossibly occurring rest potentials in the windings 68 with the doors areopen, the potentials at the bases of the transistors 29, 30 and 31 aresuch that the bases can never become negative with respect to theiremitters.

The potential induced in the coil 68 of the transmitting elements 27causes the base of the transistor 31 to hecome negative with respect toits emitter and thereby causes its collector-emitter circuit to becomeconductive. A pulsating direct current now flows from the conductor 101through the transistor 31 and resistor 37 to the conductor 102; thiscauses the potential on the point 136 to become negative with respect toits previous potential when transistor 30 was non-conductive, therebythe transistor 30 becomes selective for the potential induced in thewinding 68 of the transmitting element 26. Thus, the base of thetransistor 30 can only become negative with respect to its emitter whenthe induced potential in the winding 68 of the transmitting element 26is fully present. Consequently, a pulsating direct current flows fromthe conductor 181 through the transistor 30 and the resistor 36 to theconductor 102; this causes the potential at the point 137 to becomenegative, whereby the transistor 29 becomes selective in the same manneras transistor 39. Now, if there is also an induced potential in thewinding 68 of the transmitting element 25, then the transistor 29 alsobecomes conductive, and a pulsating direct current is able to flow fromthe conductor 101 by way of the transistor 29 and the relay RT3 to theconductor 102 causing the relay RT3 to become energized and operative.

A practical example of the control circuit will be illustrated by thefollowing explanations and example. The transmitting elements 1 and 2are excited or energized since the gripping or safety and slack cablecontrols have not responded. Relay RT1 is energized so that contactswitch K'RTI is closed. Since all doors are closed, the transmittingelements 11, 12 and 13 are excited, so that relay RT2 is energized andcontact switch KRTZ is closed. Since the cab 94 is at the second stop orfloor, the corresponding door is not locked, so that the winding 68 ofthe transmitting element 26 is free from voltage, the relay RT3 isdeenergized and the contact switch KRT3 is open and relay coils RUI andRUZ cannot be energized.

If one now operates, for example, the outside call button DAl, which ison the first floor, a direct current flows from the conductor 101 by wayof the braking magnet contact KMB and the push button DAl and attractsthe relay RS1. This causes switch contact K2RS1 to close and to energizethe relay RV2 by way of switch contacts KJS1 and K2RV1. The holdingcircuit of the floor relay RS1 is closed by way of the switch contactsK1RV2 and K1RS1. The operation of the relay RV2 causes the contact K3RV2to close and to energize the locking magnet MV. The movable slideway 98is attracted and the locking bolt 63 locks the door of the transmittingelement 26 causes the relay R3 to be energized and the switch contactKRTS to close, so that relay RU1 is energized through the circuit of theswitch contacts K4RV2, K2RU2. By means of the contact KIRUI the brakingmagnet solenoid MB is energized and the brake shoe is removed from thebrake disc of the brake 91. The motor now sets the elevator cab 94 indownward motion from the second stop to the first stop.

As soon as the cab 94 approaches the first stop, the shaft switch 181 isactuated by the slideway 97. The switch contact KJSI opens, relay RV2and relay RUI are deenergized, the braking solenoid MB becomesdeenergized and the brake 91 becomes operative to prevent motor 90 fromoperating cab 94. The locking magnet MV is deenergized, and the movableslideway 98 unlocks the door locking mechanism 68.

In the example described above, the three parts of the safety circuithave each their own operating member and switching arrangement. But, inmost cases it will be advantageous to use the same switching arrangementfor all three parts.

While there has been shown what is at present considered to be apreferred embodiment of the invention, it is apparent that many changesand modifications may be made therein without departing from the scopeof the invention, and it is intended in the accompanying claims to coverall such changes and modifications as fall within the true spirit of theinvention.

What is claimed is:

1. In an elevator control system having an elevator cab movable within ashaftway provided for each stop or floor, the elevator cab being coupledto a reversible driving motor through a braking device, a shaftway doorprovided for each floor -for entry into said cab and a safety circuitfor preventing movement of said cab with an open cab door and openshaftway door comprising magnetically saturable transmitting elements:including a transistor having a collector-emitter circuit and a basecircuit, a relay coupled in said collector-emitter circuit and operativein response thereto when rendered conductive, said transmitting elementsbeing coupled to said base circuit to energize the same to render saidcollector-emitter circuit conductive, said relay being coupled to saidsafety circuit for interrupting the same when deenergized; saidtransmitting elements comprising a first winding coupled to a source ofAC. potential, a second winding coupled to said base circuit and amovable core having a first and a second part, said first part beingformed of saturable magnetic material and said second part being formedof non-magnetic material, said first winding being magnetically coupledto said second winding with said first part of said core positionedtherein and being magnetically decoupled with said second partpositioned therein; a voltage balancing network coupled to saidcollector-emitter circuit and through said second winding to said basecircuit to provide a bias thereto to maintain said collectoremittercircuit non-conductive with said second winding magnetically decoupledfrom said first winding, said first part of said core when positionedwithin said windings magnetically coupling said first winding to saidsecond winding to render said collector-emitter circuit conductive andenergize said relay.

2. The elevator control system as claimed in claim 1, in which said corepart forms part of an emergency control circuit, said second core partbeing positioned Within said first and second windings to decouple sameto prevent operation of said elevator cab, and including a limitingdiode coupled between said base and said emitter.

3. In an elevator control system having an elevator cab movable within ashaftway provided for each stop or floor, the elevator cab being coupledto a reversible driving motor through a braking device, a shaftway doorprovided for each floor for entry into said cab and a safety circuit forpreventing movement of said cab with an open cab door and open shaftwaydoor comprising magnetically saturable transmitting elements: includinga transistor having a collector-emitter circuit and a base circuit, arelay coupled in said collector-emitter circuit and operative inresponse thereto when rendered conductive, said transmitting elementsbeing coupled to said base circuit to energize the same to render saidcollector-emitter circuit conductive, said relay being coupled to safetycircuit for interrupting the same when deenergized; said transmittingelements being provided for each stop and com prising a first and asecond coil coupled to a door frame and a core element coupled to a doorassociated with said door frame, said core element when positionedwithin said first and second coils causing said coils to becomemagnetically responsive to each other whereby to energize said secondcoil when said first coil is energized; and including a transistorelement for each said second coils, the base of each said transistorelements being coupled to one end of each said second coilsrespectively, the emitter-collector circuits of said transistor elementsbeing serially connected to a source of potential and a voltagebalancing network for each said second coils and transistor elements,the other end of each said second coils being coupled to its associatedvoltage balancing network, said voltage balancing network beingeffective to maintain the emitter-collector circuit of each saidtransistor elements non-conductive with the second coil associatedtherewith being deenergized;

4. The elevator control system as claimed in claim 3, including a relaycoupled to said emitter-collector circuits and operable in responsethereto when rendered conductive to operate said safety circuit wherebyto permit the elevator cab to be moved within the shaftway.

5. The elevator control system as claimed in claim 4, in which each saidvoltage balancing network comprises. first, second, nth and n+1 seriallyconnected resistors coupled to a source of reference potential, saidother end of one of the secondary coils being coupled to the collectorof said transistor associated therewith through said first resistor andsaid relay, said other end of a second one of said secondary coils beingcoupled to the collector of said transistor element associated therewiththrough said second and first resistors, said relay and saidemittercollector circuit of said first-mentioned transistor element, andsaid other end of an nth one of said secondary coils being coupled tothe collector of said nth transistor element associated therewiththrough said nth, second and first resistors, said relay and saidemitter-collector circuits of said first and said second-mentionedtransistor elements, so that potentials induced in said secondary coilsact by way of the base-emitter circuits of said transmitting elements torender said emitter-collector circuits conductive to energize said relaywhen all said emittercollector circuits are rendered conductive.

6. The elevator control system as claimed in claim 5, in which said coreelement comprises a first and a second leg of saturable magneticmaterial to etfect'a positive coupling between said first and secondcoils to induce a potential therein when a potential is applied to saidfirst coil and said first and second legs are inserted in said first andsaid second coils, respectively, said base circuit rendering saidemitter-collector circuit associated therewith conductive when said corelegs are inserted into said coils and said potential is applied to saidfirst coils.

7. In an elevator control system having an elevator cab movable within ashaftway provided for each stop or floor, the elevator cab being coupledto a reversible driving motor through a braking device, a shaftway doorprovided for each floor for entry into said cab and a safety circuit forpreventing movement of said cab with an open cab door and open shaftwaydoor comprising magnetically saturable transmitting elements: includinga transistor having a collector-emitter circuit and a base circuit, arelay coupled in said collector-emitter circuit and operative inresponse thereto when rendered conductive, said transmitting elementsbeing coupled to said base circuit to energize the same to render saidcollector-emitter circuit conductive, said relay being coupled to safetycircuit for interrupting the same when deenergized; a transistor elementcoupled to said transmitting element for each of 11 sto s, thecollectors of each said transmitting elements being coupled together, avoltage balancing network for each said transistor element, each saidtransmitting element being coupled to a base of its associatedtransistor and its associated voltage balancing network to maintain saidbase positive with respect to the emitter of its associated transistorelement when there is no potential applied to the base by thetransmitting element and to render said base negative with respect tosaid emitter to cause the emitter-collector circuit to become conductivewhen a potential is applied to said base by said transmitting element.

8. The elevator control system as claimed in claim 7, in which a relayis coupled to said emitter of one of said transistor elements and aresistor device is provided for each and coupled to said emitter of saidother transistor elements, said relay being energized when saidemitter-collector circuits of each said transistor elements are renderedconductive and a current passes through each said resistor devices.

9. The elevator control system as claimed in claim 8, including acapacitor for each said resistor devices and said relay by-passing thesame to smoothen the pulsating current flowing in the emitter-collectorcircuits.

10. The elevator control system as claimed in claim 8, in which saidtransmitting elements each include a first core element, a first windingon said first core element, a second core element juxtaposed to saidfirst core element with an air gap provided therebetween, a secondwinding on said second core element and a magnetic short-circuitingelement movable from a first position within said air gap and betweensaid core elements and a second position removed from said air gap, saidfirst winding when a potential is applied thereto induces a potentialinto said second winding when said magnetic short-circuiting element isin said second position and induces no potential into said secondwinding when said magnetic short-circuiting element is in said firstposition, said first position indicating that a shaftway door isunlocked and said second position indicating that said shaft- Way dooris locked; said second winding having one end coupled to the base of itsassociated transistor element and another end coupled to its associatedvoltage balancing network and when said second winding is renderedconductive, the emitter-collector circuit of its associated transistorbeing rendered conductive.

11. The elevator control system as claimed in claim 8, in which saidtransmitting element comprises a first winding, a second winding andmeans magnetically coupling said windings to induce a potential intosaid second winding when a potential is induced into said first winding;

one end of said second winding being coupled to the base of itsassociated transistor and the other end of said second winding beingcoupled to its associated voltage balancing network.

12. The elevator control system as claimed in claim 11, in which eachsaid voltage balancing networks comprises a first and a second resistorelement coupled together at a common point to said other end of saidsecond winding, said first and second resistor elements being seriallyconnected through said common point, there being n serially connected"resistor elements, one end of each of said n-1 serially connectedresistor elements being coupled to the emitter of a transistorassociated with another one of said n serially connected resistorelements through one of said resistor devices to a source of referencepotential, the one end of the nth serially connected resistor elementsbeing coupled directly to a source of potential which is negative withrespect to said source of reference potential and said other end of eachof said serially connected resistor elements being coupled to a sourceof potential which is positive with respect to said source of referencepotential, said emitter-collector circuits of said transistor elementwhen conductive cause the emitter thereof to become more negativewhereby said one end of said nl serially connected resistor elementsbecome more negative to cause the base element of another one of the ntransistors to become more negative and render its associatedemitter-collector circuit conductive.

13. The elevator control system as claimed in claim 12, in which saidrelay is coupled directly to the emitter of the nth transistor so thatthe emitter-collector circuits of all n transistors must be renderedconductive by said transmitting elements.

14. The elevator control system as claimed in claim 13, includingnormally open switch contacts and normally deenergized relay controlscoupled to and responsive to the energization of said relay, said relaywhen energized being efiective to energize said relay controls and closesaid normally open switch contacts to permit said elevator cab to movewithin the shaftway.

References Cited in the file of this patent UNITED STATES PATENTS265,448 Sawyer Oct. 3, 1882 963,570 Humphrey July 5, 1910 1,344,430Wigmore June 12, 1920 2,378,218 Hard June 12, 1945 FOREIGN PATENTS1,093,539 France Nov. 24, 1954

